La Canebiere is Marseille's Champs Elysees. Modelled on the famous Parisian boulevard, it is a wide stretch leading straight up from Vieux Port (Old Port) for about 3/4 mile (1 km). it does not quite have the elegance of the Champs Elysees being a little more a hotch-potch of shops, hotels, and restaurants, but it is a great place to get the feel of the city. Named after the city's thriving trade is nautical rope in the Middle Ages - canabe being the French word for cannabis or hemp from which the rope was made - the street is now the spine of the thriving city.
La Canebiere acts as a divider between different city districts. To its west there is the modern shopping mall Centre Bourse, to the south is the moneyed district, and to the north you'll find the quartier Belsunce where you can buy just about anything from the local Arab community if you're prepared to haggle with the street-traders. Behind the Centre Bourse is the Jardin des Vestiges, the ancient port center. Excavations here have turned up all sorts of things including bits of the 3rd century BC Greek city. Most of the finds, and an old Roman trading boat, can be seen in the Musee d'Histoire de Marseille in the Centre Bourse. Further up the street is the Musee de la Marine (in the stock exchange building) which has the nautical history of Marseille.
La Canebiere runs in a straight line up from Vieux Port, the Old Port. Catch the metro to Vieux Port and walk up the boulevard. Alternately start in the middle at metro station Noailles. Or you can hop of the new tram, inaugurated in 2007 and head to Canebiere Garibaldi station. The Musee d'Histoire is open Mon-Sat, the Musee de la Marine is open Wed-Sun.